Mechanism for incremental movement of vertical frame

ABSTRACT

Apparatus for incrementally moving a planar frame, such as a die support frame used in the manufacture of semiconductor components. The apparatus includes means for mounting a frame for movement in a vertical plane past a heater element, whereby portions of the frame can be successively heated by the heater element to permit bonding of die to leads terminating at the upper margin of the frame. The frame is incrementally moved by one or more horizontally reciprocal pawls, each pawl being receivable within an opening in the frame during a feed stroke of the pawl and being cammed out of such opening during a return stroke thereof. A first clamp releasably clamps the frame to the heater element during a die bonding operation and moves away from the heater element at the end of the return stroke and during the feed stroke. One or more drag clamps releasably clamp the lower margin of the frame against a support during the return stroke and through a major portion of the feed stroke, the drag clamps moving away from the support during the latter part of the feed stroke to permit the frame to gravitate if it has elevated during the feed stroke.

MOVEMENT OF VERTICAL FRAME lnventor:

John C. Diepeveen, 1737 Kimberly Dr., Sunnyvale, Calif. 94087 Filed:

Mar. 16, 1973 Appl. No.: 342,231

U.S. Cl

Int. Cl

............. B23k l/00, B23k 37/04 Field of Search 228/4, 47; 29/203 R;

Primary Examiner-Francis S. l-lusar Assistant Examiner--Robert J. Craig United States Patent [191 [111 3,85,74

Diepeveen .lan. 7,1975

[54] MECHANISM FOR INCREMENTAL 57 ABSTRACT Apparatus for incrementally moving a planar frame, such as a die support frame used in the manufacture of semiconductor components. The apparatus includes means for mounting a frame for movement in a vertical plane past a heater element, whereby portions of the frame can be successively heated by the heater element to permit bonding of die to leads terminating at the upper margin of the frame. The frame is incrementally moved by one or more horizontally reciprocal pawls, each pawl being receivable within an opening in the frame during a feed stroke of the pawl and being cammed out of such opening during a return stroke thereof. A first clamp releasably clamps the frame to the heater element during a die bonding operation and moves away from the heater element at the end of the return stroke and during the feed stroke. One or more drag clamps releasably clamp the lower margin of the frame against a support during the return stroke and through a major portion of the feed stroke, the drag clamps moving away from the support during the latter part of the feed stroke to permit the frame to gravitate if it has elevated during the feed stroke.

18 Claims, 7 Drawing Figures PATENTED JAN 71975 SHEET 1 [IF 2 MECHANISM FOR INCREMENTAL MOVEMENT OF VERTICAL FRAME This invention relates to the handling of generally planar frames, such as die support frames used in the manufacture of semiconductor components and, more particularly, to apparatus for incrementally -moving such a frame past a reference point while the frame is vertically disposed.

BACKGROUND OF THE INVENTION In the manufacture of semiconductor components, such as diodes, transistors and integrated circuits, semiconductor chips or die are secured to die support frames by being bonded thereto after the frame has been heated. Generally, a number of frame portions which are to receive the die are heated by moving the frame so that the frame portions are successively moved into thermal interchange relationship with a heater element. In some frames, the pads or regions which receive the die are located centrally of the frame and leads extends outwardly from the pads. In such a case, the frame is horizontally disposed when the frame portions are heated by the heater element. This is accomplished by moving the frame over the heater element. I

In other applications, the frame has leads terminating at one side margin of the frame and it is at the ends of each pair of such leads that a die is to be bonded. In such a case, it is most advantageous to orient the frame in a vertical plane so that the upper extremity of the frame defines the side margin thereof to which the die are to be attached. A need has, therefore, arisen to provide apparatus for supporting a frame of this type in a vertical plane and to move the frame incrementally past a heater element, whereby successive portions of the frame can be heated to permit die bonding operations to be carried out with the frame.

SUMMARY OF THE INVENTION This invention relates to an apparatus for satisfying the above need yet assures complete control of the frame at all times during bonding operations therewith. Control of the frame is especially important because of the tendency of a planar frame, which disposed in a vertical frame, to be elevated slightly when it is moved in a horizontal direction by a force applied above its lower margin. If the frame is moved incrementally, the cumulative effect of the individual elevations is that the frame will rise too much and be out of the proper position with respect to a certain reference. Moreover, the frame must be clamped against movement during the time when the drive means reverses, i.e., during a return stroke thereof. Otherwise, the frame could possibly move rearwardly with the drive means and thereby be dislocated relative to the reference, rendering the apparatus inoperable for its intended purpose.

The present invention overcomes the aforesaid problems by the use of one or more drag clamps releasably engageable with the frame in a manner and for a time sufficient to achieve control of the frame during both forward and reverse movement of the drive means. Specifically, the clamps hold the frame stationary during reverse movement of the drive means and apply drag forces to the frame during only a portion of the forward movement of the drive means. However, the frame moves forwardly notwithstanding the drag forces thereon. During the remainder of the forward movement, the drag clamps are out of engagement with the frame, thus allowing it to continue its forward movement to descent to the support therebeneath if, in fact, it has risen during the forward movement.

The foregoing feature assures that the frame will be properly oriented relative to a heater element at one side of the vertical plane of the frame. Thus, successive portions of the frame will move into and out of heat exchange relationship to the heater element so that semiconductor chips or die can be successively bonded to the upper extremities of the frame portions.

The frame is generally formed with spaced leads de fining openings therethrough. The frame drive means of the apparatus of this invention includes one or more reciprocal pawls adapted to enter the openings at the end of the reverse movement of the drive means and to advance the frame forwardly during the forward movement of the drive means. The control of the frame is provided by the drag clamps during such forward and reverse movements and assures that the openings of the frame will at all times be properly oriented so that the pawls will readily enter the openings at the end of each reverse movement of the drive means. Thus, there will be no malfunction of the pawls or damage to the frame due to improper alignment of the openings relative to the pawls. 7

Another feature of the invention is the provision of a frame support which orients the frame in a vertical plane yet allows for some slight bowing or crookedness of the frame. Each pawl is shaped and mounted in an operative position such that the leading edge of the pawl forms an acute angle with the plane of the frame. Thus, such leading edge, when it engages the frame during forward movement thereof, prevents lateral movement of the frame and thereby overcomes any tendency of the frame to move suddenly to the side which might cause a die just previously bonded to the frame to be flipped off the same during forward movement thereof.

The primary object of this invention is to provide an improved apparatus for supporting a die support in a vertical plane and for incrementally moving the frame past a heater element in a manner to control the movement of the frame so that it is presented properly to the heater element at all times notwithstanding the tendency for the frame to be elevated relative to its support therebeneath during its forward movement to thereby-assure substantially automatic movement of the frame without the need for operator attention.

Another object of this invention is to provide apparatus of the type described wherein the apparatus utilizes a reciprocal pawl for entering an opening in the frame during a return stroke and for driving the frame in a forward direction during a feed stroke while at the same time clamp means applies a holding force to the frame during the return stroke and a drag force to the frame for at least a major portion of the feed stroke to assure that control of the frame is maintained at all times yet the frame is allowed to gravitate to an equilibrium position if, during the feed stroke, the frame rises slightly due to the fact that the moving force applied to the frame is exerted above the lower margin thereof.

A further object of this invention is to provide an apparatus of the aforesaid character wherein the pawl is shaped to prevent lateral movement of the frame during a feed stroke so that a die bonded to the frame at the upper margin thereof will not be thrown off the frame such as by a sudden lateral movement of the frame due to one or more causes.

Still another object of this invention is to provide apparatus of the type described wherein the frame is incrementally moved automatically by the actuation of a drive means which is cycled successively and, during each cycling step, causes the frame to be advanced through an incremental distance, whereby a number of different portions of the frame can be successively moved into heat exchange relationship to a heater element adjacent to one side of the frame to permit the bonding of semiconductor chips or die to respective terminals at the upper margin of the frame.

Other objects of this invention will become apparent as the following specification progresses, reference being had to the accompanying drawings for an illustration of the apparatus.

IN THE DRAWINGS:

FIG. 1 is a top plan view of the die frame supporting and moving apparatus of this invention;

FIG. 1a is an enlarged, fragmentary, cross-sectional view of the apparatus showing the way in which a reciprocal pawl advances a die frame in one direction;

FIG. 2 is a front elevational view of the apparatus, parts being broken away to illustrate details of construction;

FIG. 3 is a bottom plan view of the apparatus, parts being broken away to illustrate details of construction;

FIG. 4 is a cross-sectional view taken along line 44 of FIG. 2;

FIG. 5 is a cross-sectional view taken along line 55 of FIG. 2; and

FIG. 6 is a timing chart showing the time intervals in which several frame clamps are in engagement with and disengaged from a frame carried by the apparatus. The apparatus of this invention is broadly denoted by the numeral 10 and includes a base comprised ofa pair of upright, generally parallel end walls 12 and 14 (FIGS. 2 and 3) which are secured to the lower surfaces of a pair of generally horizontal top plates 16 and 18 (FIGS. 1, 4 and 5). Plates l6 and 18 are spaced apart as shown in FIGS. 1 and 5 to present a gap 20 therebetween for receiving a generally planar die support frame 22 when the latter is disposed in a generally vertical plane. Frame 22, when manually inserted into the gap at the upstream end thereof, i.e., the right end thereof when viewing FIG. 1, and when coupled to frame drive means 30 hereinafter described, is adapted to be incrementally moved through gap 20 past a heater element 24 disposed in a recess 26 in plate 16 as shown in FIG. 1. An operator successively places integrated circuit chips at the upper margins of portions of frame 22 which are successively moved into engagement with heater element 24. Such upper margins of the frame portions are defined by the upper ends of respective pairs of spaced leads 28 (FIGS. la and 2), whereby the chips willv be bonded to such upper ends due to the heat generated in the frame portions by heater element 24. A handrest 32 is provided for the tween end walls 12 and I4. Crosspiece 38 has an upper surface 39 (FIG. 2) to which a bracket 40 is secured for adjustably mounting a pair of tubular posts 42 which extend upwardly from the bracket. Heater element 24 is mounted on the upper ends of posts 42 and can be adjusted in height by adjusting posts 42 relative to bracket 40. Crosspiece 38 has a pair of holes 44 (FIG. 2) therethrough aligned with posts 42 to increase the distance by which the posts can be lowered. Also, holes 44 allow air to pass through posts 42 for cooling purposes.

operators benefit, the handrest being secured by As shown in FIG. 1, heater element 24 has a generally flat face 46 against which successive portions of frame 22 are to engage so as to be heated thereby. A central clamp 48 (FIGS. 1 and 2) releasably holds each frame portion against face 46.

A U-shaped heat shield 50 of reflective material, such as a suitable metal, is carried on posts 42 to reflect heat energy radiated to the side by heater element 24. To this end, heat shield 50 has a pair of opposed parallel sides 54 (FIG. 4) beneath and spaced from respective top plates 16 and 18 and integral with a bottom 56 which rests loosely on cotter pins 52 passing through respective posts 42; thus, there is a minimum of heat conduction from the posts to heat shield 50.

Plate 16 has a pair of spaced, horizontally aligned guid rails 58 which are secured to and depend from side margin 60 of the plate adjacent to and on one side of gap 20 (FIG. 1). Rails 58 are spaced apart to accommodate heater element 24 therebetween as shown in FIG. 1.

Top plate 18 has a pair of spaced rails 62 secured to and depending from side margin 64 thereof on the 0pposite side of gap 20 from rail 58. Rails 58 and 62 define guides from frame 22 when the latter is disposed within gap 20. The width of gap 20 and the distance between corresponding rails 58 and 62 are generally greater than the basic width of frame 22. This feature allows the frame to be movable through the gap even though the frame is not truly flat, such as when it is slightly bent or bowed at one or more locations thereon. A rigid strip 66 (FIGS. 4 and 5) is secured by screws 68 to the lower, flat faces of rails 58. Strip 66 provides a support on which frame 22 rests and is sliadble when the frame is disposed in gap 20 in a vertical plane.

Plate 16 is provided with a pair of bearing blocks 70 and 72 (FIG. 3) secured by screws 74 and 76 to its lower surface 77 slightly inwardly of end walls 12 and 14. Bearing blocks 70 and 72 shiftably mount a horizontal shaft 78 for reciprocal movement with respect to plate 16. Shaft 78 has a pair of spaced brackets 80 and 82 (FIGS. 1 and 3) releasably clamped thereto by screws-84 and 86, (FIG. 1) respectively, brackets 80 and 82 being secured by screws 88 and 90, respectively to the end faces of a pair or rigid plates 92 and 94, respectively, which project toward each other as shown in FIG. 1 and are cantilevered on respective brackets 80 and 82. Shaft 78, brackets 80 and 82, and plates 92 and 94 form parts of drive means 30.

Each of plates 92 and 94 is provided with a pawl 96 (FIG. 1) pivotally mounted by a vertical pin 98 on the upper surface of the corresponding plate, the pawl being biased by a coil spring 100 in a counterclockwise sense when viewing FIG. 1 toward and against a' stop pin 102 carried by the plate. The length of each pawl 96 is sufficient to cause it to extend through a slot 104 (FIGS. 1 and 2) extending into the corresponding rail 58 from the inner end thereof. Thus, each pawl projects normally across the vertical plane in which gap lies.

Each pawl has a leading edge 96a which converges with a trailing edge 96b to form a point, the latter adapted to be inserted within a space 97 (FIG. 1a) between adjacent pairs of leads 28 of frame 22 when the pawl has moved in reverse, i.e., to the right when viewing FIG. 1, during a return stroke. When the pawl is in opening 97, it is in the proper position for advancing frame 22 forwardly during a feed stroke. As shown in FIG. 1a, leading edge 96a makes an acute angle a with the plane of frame 22. Thus, the frame is held against lateral movement between guide rails 58 and 62 during the feed stroke even though the thickness of the frame is less than the distance between rails 58 and 62.

Shaft 78 and thereby brackets 80 and 82 are reciprocated by operation ofa stepping motor 106 (FIGS. 1, 3 and 4) carried by sidewall 34 and projecting laterally therefrom. The drive shaft 108 (FIG. 2) of motor 106 has a cam 110 provided with a cam surface lI2 which normally engages a roller II4 on a first lever 116 pivotally mounted by a pin 118 on a first bearing plate 120 transverse to and mounted on crosspiece 38. The opposite end of lever 116 has a rod 122 (FIG. 4) adjustably and pivotally mounted thereon and extending upwardly therefrom, the upper end of pin 122 being pivotally received within a recess (not shown) in the lower flat face of a second lever 124 extending transversely of first lever 116. Second lever 124 extends toward and is rigidly connected to a horizontal shaft 126 which spans the distance between and is rotatably mounted on first bearing plate 120 and a second bearing plate 128 (FIG. 2) parallel to first bearing plate 120 and secured to crosspiece 38. Clamp 48 is secured by screws 130 to an end face of lever 124 on the side of shaft 126 opposite to the side on which rod 122 is disposed. Clamp 48 has an inclined finger 134 at its upper end which extends across the upper margin of the adjacent side 54 of heat shield 50 and toward face 46 of heater element 24 as shown in FIG. I. Finger I34 is adapted to clamp a portion of frame 22 against face 46 of heater element 24.

A bracket I13 (FIGS. 2, 3 and 5) is clamped to shaft 78 and is coupled to cam 110 by a roller 115 eccentrically mounted on the cam relative to drive shaft 108 (FIG. 2). Roller 115 is slidably received within a guideway 117 (FIGS. 3 and 5) and moves vertically in the same direction as the cam rotates under the influence of drive motor 106 and as bracket I13 reciprocates horizontally under the influence of the rotation of roller 115 about the axis of drive shaft 108. Thus, bracket 113 causes shaft 78 to reciprocate in response to the operation of motor 106.

A first guide shaft 119 (FIGS. 2, 3 and 5) spanning the distance between end wall 12 and first bearing plate I20 is slidably engaged by and guides the lower end of bracket 113 (FIG. 5) as it reciprocates and prevents it from rotating about the axis of shaft 78. As shown in FIG. 5, bracket 113 is bifurcated to receive shaft 1119. Moreover, bracket 80 (FIG. 5) has a lower portion 121 provided with a vertical surface 123 which slidably bears against and is guided by shaft 119 as bracket 80 reciprocates under the influence of shaft 78.

A second guide shaft I (FIGS. 2, 3 and 4) spans the distance between second bearing plate 128 and end wall 14 and is axially aligned with and serves a similar purpose as shaft 119. Shaft 125 guides the lower portion 127 (FIG. 2) of bracket 82 and prevents it from rotating about the axis of shaft 78.

A limit switch (FIGS. 3 and 5) secured to the inner surface of sidewall 34 has an actuator arm 142 provided with a roller 144 which bears against the cylindrical outer surface 146 of a sleeve 148 mounted on drive shaft 108. Switch 140 forms a part of an electrical circuit (not shown) which limits the rotation of drive shaft 108 to a single revolution at the end of which motor 106 is deactuated. A push-button switch 150 having a plunger 152 (FIG. 3) is provided for manual operation of motor 106. Switch 150 could also take the form of a foot-actuated switch, if desired.

An important feature of the present invention is the way in which the lower margin of frame 22 is provided with a drag force during a portion of the time in which the frame is moved incrementally to the left when viewing FIGS. 1 and 2 under the influence of pawls 96. To this end, a pair of L-shaped drag clamps I60 and 162 (FIGS. 2 and 4) are rotatably mounted on shaft 126 at the ends thereof outboard of bearing blocks 120 and 128 (FIG. 2). A coil spring 164 is provided for each drag clamp, respectively, the spring being connected at one end to a respective drag clamp and to the opposite end to a post 166 (FIG. 4) secured to and extending up wardly from the adjacent bearing block (FIG. 2). Thus, the drag clamps are biased in a clockwise sense when viewing FIG. 4 about shaft 126, each drag clamp being secured by screws 168 (FIG. 4) to a bracket I70 freely rotatably on shaft 126. As shown in FIG. 4, the illustrated drag clamp normally bears against the lower margin of the adjacent rail 58 when frame 22 is not in an operative position in gap 20. When frame 22 is in the gap, each drag clamp forces it into frictional engagement with the adjacent rail 58. Also, drag clamps and 162 cooperate with central clamp 48 to hold the frame against rearward movement in gap 20 as pawls 96 move through their return stroke.

Each drag clamp has an actuating lever I72 immediately adjacent thereto. Each lever 172 has a lateral pin 174 (FIG. 2) which extends toward the drag clamp and is adapted to engage the vertical portion thereof and to rotate the drag clamp in a counter-clockwise sense when viewing FIG. 4 when lever 172 is rotated under the influence of shaft 126. Initially, each pin 174 is spacedfrom the vertical portion of the corresponding drag clamp. Thus, the drag clamp does not rotate until shaft 126 has rotated through a predetermined arc. Each lever is adjustably connected to shaft 126; thus, the spacing between each pin 174 and the corresponding drag clamp can be varied. In this way, it is possible to delay the rotation of the drag clamps relative to that of shaft 126 as desired. Moreover, this feature permits central clamp 48 to be rotated out of engagement with the upper part of the frame as drag clamps I60 and 162 continue to clamp the lower part of the frame to rails 58.

OPERATION Apparatus I0 is initially placed on a supporting surface and motor 106 and heater element 24 are coupled to a source of electrical power. A die support frame 22 is inserted in gap 20 at the entrance end, i.e., the righthand end when viewing FIGS. I and 2. The frame is caused to rest on strip 66 and then is moved to the left until the right-hand pawl 96 (FIG. I) extends through the first space 97. In this position of the frame, the first pair of leads will usually be out of alignment with face 46 of heater element 24. Thus, the frame will be moved incrementally to the left when motor 106 is cycled one or more times until the first pair of leads 28 are aligned with face 46 of heater element 24.

Each time the motor is cycled, cam 110 rotates through one revolution and, as it does, rotates roller 115 which, in turn, moves bracket 113 and thereby shaft 78 to the right (viewing FIG. 3) through a first distance, then to the left through a second distance, and finally again to the right through a third distance. The first distance is selected so that it is greater than the third distance but is less than the second distance. During the movement of shaft 78, both pawls 96 are shifted accordingly. During the initial cycling of motor 106, the right-hand pawl is normally out of a space 97 and remains so during its return stroke until it is free to enter the next space 97 which it does under the influence of its spring 100. It enters space 97 at the end of its return stroke. Then, shaft 78 moves to the left and the pawl inserted into a space 97 drives the frame to the left during the feed stroke until the next pair of leads 28 moves into alignment with face 46 of heater element 24. Then, to complete the cycling of the motor, each powl is then returned to a position about three-fourths of the way through its return stroke, at which time motor 106 is deactuated by the action of switch 140 (FIG. 3) to await the next cycling step. During this wait period, a bonding operation takes place wherein a die is bonded to the upper ends of the pair of leads aligned with face 46 of heater element 24.

During the initial portion of each cycling step, the pawls move to the right and central clamp 48 and drag clamps 160 and 162 remain in engagement with the frame, thus holding the frame against movement to the right such as by being frictionally engaged by the pawls. However, as the pawls approach the end of the return stroke, cam 110 causes lever 116 to rock through a small arc in a counterclockwise sense (viewing FIG. 2) about pin 118 so that central clamp 48 moves out of clamping relationship to the frame. Thus, the movement of the frame during the feed stroke is assured and central clamp 48 will not mar the surface of leads 28 as the frame moves. The opening of central clamp 48 is denoted by the darkened timing segment 200 (FIG. 6). Then, during the feed stroke, central clamp 48 is maintained out of clamping relationship to the frame as denoted by darkened timing segment 202.

Drag clamps 160 and 162 remain in clamping relationship to the frame at all times during the return stroke and through a major portion of the feed stroke. Finally, during the latter part of the feed stroke, drag clamps 160 and 162 open, i.e., they move out of clamping relationship to the frame as denoted by darkened timing segment 206. It is during this period that all three clamps are spaced from the frame; thus, the frame is allowed to gravitate onto strip 66 if, during the feed stroke, the frame had risen. In this way, the frame movement is under the control of the drag clamps at all times to assure that the frame will be properly oriented relative to heater element 24.

The delay in opening the drag clamps is achieved by positioning the pins 174 on levers 172 a distance sufficient to prevent movement of the drag clamps until shaft 126 has rotated through a predetermined arc. The shape of the cam and its relationship to the motor drive shaft are chosen to achieve the movement of the drag clamps as mentioned above.

The foregoing steps of each cycle are repeated over and over again until the frame has moved incrementally past heater element 24. During the bonding of die to the left end portion of the frame, only the right-hand pawl will drive the frame. During the bonding of die to the central portion of the frame, both pawls will drive the frame. During the bonding of die to the right-hand frame portion, only the left-hand pawl will drive the frame.

I claim:

1. Apparatus for handling a planar frame comprising: a support; means on the support for positioning a planar frame in a vertical plane for movement along a predetermined path relative to the support; means adjacent to said path for applying heat to a portion of the frame when the latter is in said plane; actuatable means shiftably mounted on the support for moving the frame relative thereto through an incremental distance along said path; means coupled with said moving means for actuating the same; and means movable transversely of said plane and relative to said support in response to the actuation of the moving means for releasably clamping the frame to the support heat applying means.

2. Apparatus as set forth in claim 1, wherein said frame has a plurality of openings therethrough, said moving means including a pawl, means adjacent to said path for mounting the pawl for movement longitudinally of the path, the pawl being pivotally mounted on said mounting means, means biasing the pawl into a position extending across said plane, and means coupled with the pawl mounting means for reciprocating the same with respect to said support, the pawl adapted to enter an opening in the frame and to drive the frame in one diretion through said incremental distance.

3. Apparatus as set forth in claim 2, wherein said reciprocating means includes a power device having a rotatable drive shaft, a generally horizontal driven shaft shiftably mounted on said support, said pawl mounting means being secured to said driven shaft, and means responsive to the rotation of the drive shaft for reciprocating said driven shaft.

4. Apparatus as set forth in claim 1, wherein said moving means includes a base member mounted on said support for reciprocation relative thereto, a pawl pivotally mounted on the base member and biased toward a position at which it extends laterally from the base member and across said plane, the leading edge of the pawl with reference to the direction of movement of the frame normally making an acute angle with said plane.

5. Apparatus for handling a planar die support frame having a plurality of spaced openings therethrough comprising: a support; means on the support for positioning a planar die support frame in a vertical plane for movement along a predetermined, generally hori zontal path relative to the support; a heater element ad jaceent to said path and operable to apply heat to a portion of the frame aligned therewith; a pair of frameengaging pawls; means mounting the pawls in spaced relationship to each other and for reciprocation relative to the support with each pawl having means biasing the same toward said plane and into a frame opening aligned therewith, each pawl being movable out of a frame opening and away from said plane when the pawl engages the frame as the pawl moves in one direction,

each pawl being receivable in a frame opening and engageable with the frame for moving the latter along said path when the pawl moves in the opposite direction; means coupled with said pawl mounting means for reciprocating the same relative to the support; a clamp shiftably mounted on the support and having means biasing the same in a direction and by an amount sufficient to urge the frame into frictional engagement with the support; and means responsive to the movement of the pawls for moving the clamp away from the plane to thereby allow the frame to be moved along said path out of frictional engagement with the support.

6. Apparatus as set forth in claim 5, wherein said clamp is disposed to engage the lower margin of the frame.

7. Apparatus as set forth in claim 5, wherein is included a second clamp shiftably mounted on the support and disposed to clamp a portion of the frame against the heater element, said second clamp being movable away from said heater element as a function of the movement of said pawls and before the movement of the first-mentioned clamp away from said plane.

8. Apparatus as set forth in claim 5, wherein the pawls are disposed on respective sides of the heater element.

9. Apparatus as set forth in claim 5, wherein said positioning-means includes a pair of guide rails on opposed sides of said path, one of the rails having a frame support strip secured to the lower margin thereof.

10. Apparatus for handling a planar frame comprising: a support; means on the support for positioning a planar frame in a vertical plane for movement along a predetermined path relative to the support; means adjacent to said path for applying heat to a portion of the frame when the latter is in said plane; an actuatable power device; means shiftably mounted on the support and coupled with said power device for moving the frame relative thereto through an incremental distance along said path; means coupled with said power device for actuating the same; a clamp shiftably mounted on the support and movable toward and away from said plane; means yieldably biasing the clamp toward said plane; and means coupling the clamp to said power device to cause the clamp to be shifted away from said plane after the power device has been actuated for a fraction of a predetermined time interval.

11. Apparatus for handling a planar frame comprising: a support; means on the support for positioning a planar frame in a vertical plane for movement along a predetermined path relative to the support; means adjacent to said path for applying heat to a portion of the frame when the latter is in said plane; an actuatable power device having a rotatable drive shaft and operable to rotate said drive shaft through a predetermined arc each time the power device is actuated; means shiftably mounted on the support for moving the frame relative thereto through an incremental distance along said path; means coupled with said power device for actuating the same; a clamp shiftably mounted on the support; means yieldably biasing the clamp toward and across said path; and means coupled to the clamp and the drive shaft for causing the clamp to move away from the path after the shaft has rotated through a portion of said predetermined arc.

12. Apparatus as set forth in claim 11, wherein said causing means includes a cam secured to the drive shaft, a driven shaft spaced from the cam, the clamp being freely rotatable on the driven shaft, lever means connecting the driven shaft with the cam to cause rotation of the driven shaft in response to the rotation of the cam, and follower means rigid to the driven shaft and movable into engagement with the clamp after the driven shaft has rotated through a preselected arc in one direction relative to the support.

13. Apparatus as set forth in claim 12, wherein is included a second clamp rigidly attached to the driven shaft and rotatable therewith, the second clamp disposed to releasably clamp the frame against said heating means.

14. Apparatus for handling a planar frame comprising: a support; means on the support for positioning a planar frame in a vertical plane for movement along a predetermined path relative to the support; means adjacent to said path for applying heat to a portion of the frame when the latter is in said plane; an actuatable motor having a drive shaft and means defining a projection rigid to and parallel with said drive shaft; a driven shaft shiftably mounted on the support and extending transversely of said drive shaft; a bracket rigidly attached to the transverse shaft, said bracket having means shiftably coupling the same to said projection to permit reciprocation of the bracket as the projection rotates under the influence of said drive shaft; a base member rigid to said driven shaft and having an upper surface; a pawl pivotally mounted on said upper surface; means biasing the pawl toward a position extending across said plane and at an angle with respect thereto, said pawl adapted to extend through an opening in the frame and to move the latter in one direction through an incremental distance along said path as said driven shaft is moved in said one direction under the influence of said motor; means coupled with said motor for actuating the same; and means responsive to the moving means for releasably clamping the frame to the support.

15. Apparatus as set forth in claim 1141, wherein is provided a stop on said upper surface of the base member, said pawl engaging the stop when the pawl is in said position.

16. Apparatus as set forth in claim 15, wherein said bias means includes a spring coupled to one end of the pawl and to the base member and disposed to urge the pawl against said stop.

17. Apparatus for handling a planar frame comprising: a support; means on the support for positioning a planar frame in a vertical plane for movement along a predetermined path relative to the support; means adjacent to said path for applying heat to a portion of the frame when the latter is in said plane; an actuatable power device having a drive shaft extending transversely of the plane, there being a driven shaft spaced .from the drive shaft and disposed in a plane parallel to said vertical plane; means mounting said driven shaft for rotation relative to the support; a cam mounted on the drive shaft; linkage means coupling the cam to said driven shaft for rotating the latter relative to the support in response to the rotation of the cam under the influence of said drive shaft; means shiftably mounted on the support and coupled with the power device for moving the frame relative thereto through an incremental distance along said path; means coupled with said power device for actuating the same; a clamp freely rotatably on said driven shaft and biased towards upright part, said clamp moving means including a lever adjacent to the clamp and provided with a pin for engaging the upright part, said lever being rigidly coupled to said driven shaft and being circumferentially spaced from said upright part before said driven shaft commences to move through said preselected arc. 

1. Apparatus for handling a planar frame comprising: a support; means on the support for positioning a planar frame in a vertical plane for movement along a predetermined path relative to the support; means adjacent to said path for applying heat to a portion of the frame when the latter is in said plane; actuatable means shiftably mounted on the support for moving the frame relative thereto through an incremental distance along said path; means coupled with said moving means for actuating the same; and means movable transversely of said plane and relative to said support in response to the actuation of the moving means for releasably clamping the frame to the support heat applying means.
 2. Apparatus as set forth in claim 1, wherein said frame has a plurality of openings therethrough, said moving means including a pawl, means adjacent to said path for mounting the pawl for movement longitudinally of the path, the pawl being pivotally mounted on said mounting means, means biasing the pawl into a position extending across said plane, and means coupled with the pawl mounting means for reciprocating the same with respect to said support, the pawl adapted to enter an opening in the frame and to drive the frame in one diretion through said incremental distance.
 3. Apparatus as set forth in claim 2, wherein said reciprocating means includes a power device having a rotatable drive shaft, a generally horizontal driven shaft shiftably mounted on said support, said pawl mounting means beiNg secured to said driven shaft, and means responsive to the rotation of the drive shaft for reciprocating said driven shaft.
 4. Apparatus as set forth in claim 1, wherein said moving means includes a base member mounted on said support for reciprocation relative thereto, a pawl pivotally mounted on the base member and biased toward a position at which it extends laterally from the base member and across said plane, the leading edge of the pawl with reference to the direction of movement of the frame normally making an acute angle with said plane.
 5. Apparatus for handling a planar die support frame having a plurality of spaced openings therethrough comprising: a support; means on the support for positioning a planar die support frame in a vertical plane for movement along a predetermined, generally horizontal path relative to the support; a heater element adjaceent to said path and operable to apply heat to a portion of the frame aligned therewith; a pair of frame-engaging pawls; means mounting the pawls in spaced relationship to each other and for reciprocation relative to the support with each pawl having means biasing the same toward said plane and into a frame opening aligned therewith, each pawl being movable out of a frame opening and away from said plane when the pawl engages the frame as the pawl moves in one direction, each pawl being receivable in a frame opening and engageable with the frame for moving the latter along said path when the pawl moves in the opposite direction; means coupled with said pawl mounting means for reciprocating the same relative to the support; a clamp shiftably mounted on the support and having means biasing the same in a direction and by an amount sufficient to urge the frame into frictional engagement with the support; and means responsive to the movement of the pawls for moving the clamp away from the plane to thereby allow the frame to be moved along said path out of frictional engagement with the support.
 6. Apparatus as set forth in claim 5, wherein said clamp is disposed to engage the lower margin of the frame.
 7. Apparatus as set forth in claim 5, wherein is included a second clamp shiftably mounted on the support and disposed to clamp a portion of the frame against the heater element, said second clamp being movable away from said heater element as a function of the movement of said pawls and before the movement of the first-mentioned clamp away from said plane.
 8. Apparatus as set forth in claim 5, wherein the pawls are disposed on respective sides of the heater element.
 9. Apparatus as set forth in claim 5, wherein said positioning means includes a pair of guide rails on opposed sides of said path, one of the rails having a frame support strip secured to the lower margin thereof.
 10. Apparatus for handling a planar frame comprising: a support; means on the support for positioning a planar frame in a vertical plane for movement along a predetermined path relative to the support; means adjacent to said path for applying heat to a portion of the frame when the latter is in said plane; an actuatable power device; means shiftably mounted on the support and coupled with said power device for moving the frame relative thereto through an incremental distance along said path; means coupled with said power device for actuating the same; a clamp shiftably mounted on the support and movable toward and away from said plane; means yieldably biasing the clamp toward said plane; and means coupling the clamp to said power device to cause the clamp to be shifted away from said plane after the power device has been actuated for a fraction of a predetermined time interval.
 11. Apparatus for handling a planar frame comprising: a support; means on the support for positioning a planar frame in a vertical plane for movement along a predetermined path relative to the support; means adjacent to said path for applying heat to a portion of the frame when the latter is in said plane; an actuatable power device having A rotatable drive shaft and operable to rotate said drive shaft through a predetermined arc each time the power device is actuated; means shiftably mounted on the support for moving the frame relative thereto through an incremental distance along said path; means coupled with said power device for actuating the same; a clamp shiftably mounted on the support; means yieldably biasing the clamp toward and across said path; and means coupled to the clamp and the drive shaft for causing the clamp to move away from the path after the shaft has rotated through a portion of said predetermined arc.
 12. Apparatus as set forth in claim 11, wherein said causing means includes a cam secured to the drive shaft, a driven shaft spaced from the cam, the clamp being freely rotatable on the driven shaft, lever means connecting the driven shaft with the cam to cause rotation of the driven shaft in response to the rotation of the cam, and follower means rigid to the driven shaft and movable into engagement with the clamp after the driven shaft has rotated through a preselected arc in one direction relative to the support.
 13. Apparatus as set forth in claim 12, wherein is included a second clamp rigidly attached to the driven shaft and rotatable therewith, the second clamp disposed to releasably clamp the frame against said heating means.
 14. Apparatus for handling a planar frame comprising: a support; means on the support for positioning a planar frame in a vertical plane for movement along a predetermined path relative to the support; means adjacent to said path for applying heat to a portion of the frame when the latter is in said plane; an actuatable motor having a drive shaft and means defining a projection rigid to and parallel with said drive shaft; a driven shaft shiftably mounted on the support and extending transversely of said drive shaft; a bracket rigidly attached to the transverse shaft, said bracket having means shiftably coupling the same to said projection to permit reciprocation of the bracket as the projection rotates under the influence of said drive shaft; a base member rigid to said driven shaft and having an upper surface; a pawl pivotally mounted on said upper surface; means biasing the pawl toward a position extending across said plane and at an angle with respect thereto, said pawl adapted to extend through an opening in the frame and to move the latter in one direction through an incremental distance along said path as said driven shaft is moved in said one direction under the influence of said motor; means coupled with said motor for actuating the same; and means responsive to the moving means for releasably clamping the frame to the support.
 15. Apparatus as set forth in claim 14, wherein is provided a stop on said upper surface of the base member, said pawl engaging the stop when the pawl is in said position.
 16. Apparatus as set forth in claim 15, wherein said bias means includes a spring coupled to one end of the pawl and to the base member and disposed to urge the pawl against said stop.
 17. Apparatus for handling a planar frame comprising: a support; means on the support for positioning a planar frame in a vertical plane for movement along a predetermined path relative to the support; means adjacent to said path for applying heat to a portion of the frame when the latter is in said plane; an actuatable power device having a drive shaft extending transversely of the plane, there being a driven shaft spaced from the drive shaft and disposed in a plane parallel to said vertical plane; means mounting said driven shaft for rotation relative to the support; a cam mounted on the drive shaft; linkage means coupling the cam to said driven shaft for rotating the latter relative to the support in response to the rotation of the cam under the influence of said drive shaft; means shiftably mounted on the support and coupled with the power device for moving the frame relative thereto through an incremental distance along said path; means coupled with said power devIce for actuating the same; a clamp freely rotatably on said driven shaft and biased towards and through said plane, said clamp adapted to releasably clamp the frame to the support; and means coupled with the driven shaft for moving the clamp away from said plane after the driven shaft has been rotated through a preselected arc relative to the support.
 18. Apparatus as set forth in claim 17, wherein said clamp is provided with a first, upright part and a second, frame-engaging part extending laterally from the upright part, said clamp moving means including a lever adjacent to the clamp and provided with a pin for engaging the upright part, said lever being rigidly coupled to said driven shaft and being circumferentially spaced from said upright part before said driven shaft commences to move through said preselected arc. 